So, that’s it then: The Senate expense scandal is now a mortal threat to Prime Minister Stephen Harper‘s career, and the future electoral prospects of his Conservative government. And all it took, astonishingly, was two of the “accused,” Sen. Mike Duffy and Sen. Patrick Brazeau, standing up in the Red Chamber and telling, just for a few minutes apiece, their side of the story.

Sen. Pamela Wallin is still to come. But the floodgates have opened. In a sense, this is now just the start. From a PMO tactical point of view, it is a calamity.

When the history of this tawdry episode is written, this decision — whether it was made by PMO officials, or Conservatives in the Senate, or Harper himself — to seek to cut Duffy, Brazeau and Wallin loose, without pay and without due process, may well go down as the very worst in a cascade of catastrophically bad decisions. Harper must now address allegations of corruption, conspiracy, and strong-arming by his office, tantamount to blackmail. The base, one suspects, will not be pleased.

Let’s acknowledge first that no one gets away clean now, come what may. We have heard for months about profligacy in the Senate, and specifically about how Duffy, Wallin, Brazeau and the recently resigned Mac Harb padded their various expense claims. We’ve heard ad nauseam about the $90,000 cheque to Duffy from former PMO chief of staff Nigel Wright. Avarice in the Senate is now a deeply embedded narrative. Tuesday’s motions have been a long time coming, and the senators’ cris de coeur, however dramatic, are unlikely to rehabilitate them, much.

But there’s a fair question here: Can it be a coincidence that the simple narrative of culpability by these three happens to suit the prime minister’s needs so well? As Brazeau pointedly asked his colleagues Tuesday, his voice trembling with emotion: Are the rest really so clean?

Monday for the first time, driven by Conservative senators’ move for suspensions without pay, a new narrative began to emerge, from Duffy’s camp. Though not conclusive, it connected the dots in a way that hasn’t happened before. It amounts to this: Duffy had sanction from the party’s highest levels, including then Leader of the Government in the Senate, Marjory LeBreton, and Nigel Wright himself, to submit his expense claims as he did. Brazeau on Tuesday made similar assertions; everything he did, he said, was above board.

But when the story blew up in the media, Duffy became a liability, and was ordered to pay up. He refused, pointing out he’d sought and received permission from his bosses at every turn — after which the PMO devised the Wright $90,000 plan, along with “lines” that would see Duffy publicly appear to willingly repay his expenses, thereby soothing anti-fat-cat passions among the Tory base. When Duffy balked, his lawyer, Donald Bayne, said, he was threatened with political summary execution — ouster from the party and the Senate. He caved, blabbed it around too freely and the rest is history. Meantime, Brazeau says, he was deemed expendable, and made a scapegoat. Wallin will doubtless tell a similar story when her turn comes.

It’s all so strangely plausible, isn’t it? And there’s now certainly more to come. Bayne claims to have documentary evidence, in the form of emails, backing up Duffy’s account. The pressure to release them, in some public forum or other, will soon become unstoppable. Even before Tuesday evening, this cried out for hard, frank answers from Harper — concrete, specific denials, or admissions. But the prime minister has been mum. Monday in question period he reverted to old talking points. Tuesday he repeated the same lines a couple of times before handing off to his parliamentary secretary, Paul Calandra, who was then filleted like a trout by NDP Leader Tom Mulcair. Harper cannot continue ducking this, without suffering irreparable harm to his own reputation.

Here’s where this leads: If Duffy’s story is true, and he can indeed prove it, then the entire senior Conservative power structure in Ottawa is on trial. And if, as Bayne has hinted, there’s evidence the prime minister knew of the Wright-Duffy deal before May 15 — when he has said repeatedly he did not know — then Harper himself will be irreparably damaged.

There’s just one way to get to the bottom of it. The principals — including Wright, Duffy, former PMO director of issues management Chris Woodcock, LeBreton, former PMO lawyer Benjamin Perrin and indeed Harper himself, as well as Brazeau and Wallin — must tell their stories under oath, in a public forum. Emails and documents must be made public. If there’s been lying or other wrongdoing, those responsible must take their lumps — up to and including the PM himself. Absent that kind of decisive resolution, this will continue to rot away at the Conservative party, and eventually bring it down.

Here’s why letting this fester further is not a path the Conservatives should choose, despite the obvious pain of facing up to it now: Their party’s foundation is moral, in the Prairie populist and Baptist-inflected Reform Party. Conservatives won power in 2006 on a wave of popular disillusionment with Liberal arrogance and corruption. Tory loyalists, the rock-solid 30 per cent, will never desert en masse to the Grits or New Democrats. What they may do, though, if they perceive a serious moral and ethical deficit at the top, is take a break. The Liberals learned in 2004, and again in 2006, what effect that can have.

Bottom line: If Duffy and Brazeau can make an even semi-plausible case for their victimization by the PMO, then the government has a much bigger problem that any amount of deflection can possibly manage. The truth will out. Put the principals under oath, and get it over with.

I am a national political columnist for Postmedia News. My work appears in the National Post, on Canada.com, the Ottawa Citizen, Montreal Gazette, Calgary Herald, Edmonton Journal, Halifax Chronicle-Herald... read more and Vancouver Sun, among other publications. I write primarily about national politics and policy.View author's profile